Drawing and packaging nylon filament yarn



y 4, 1967 1.. D. POTTS ETAL DRAWING AND PACKAGING NYLON FIL-AMENT YARN Filed April 1 1965- 2 6 OUNCES OF TEXTURED YARN REMOVED FROM PACKAGE INVENTORS L.D. POTTS BY L. F. SMITH TORNE Y United States Patent 3,328,951 DRAWING AND PACKAGING NYLON FILAMENT YARN Larry D. Potts, Gulf Breeze, and Louis F. Smith, Pensacola, Fla., assignors to Monsanto Company, St. Louis, Mo., a corporation of Delaware Filed Apr. 1, 1965, Ser. No. 444,557 5 Claims. (Cl. 57-157) This invention relates to drawing and packaging nylon filament yarn. More particularly, the invention relates to a method of drawing and packaging nylon filament textile yarn wherein the speed of the drawing and the speed of the packaging are periodically varied during package building to improve the physical properties thereof.

Newly formed nylon filaments do not show high molecular orientation and have relatively low tensile strength as compared to highly oriented nylon filaments in which the molecules are aligned in the direction of the filament axis. To orient nylon filaments and thereby to increase greatly the strength thereof, they are stretched a desired extent using two thread advancing means operated at a predetermined peripheral speed diiferential therebetween. In a common operation the newly formed nylon filament yarn is wrapped on a spin bobbin without twist. Thereafter, the yarn is processed on a conventional drawtwister comprising nip-forming feed rolls, a draw roll and a ring twister assembly which includes a spindle clutching a yarn take-up bobbin and adapted to be rotated by a driven belt or the like. The assembly further comprises a conventional vertically reciprocatable spinning ring axially surrounding the bobbin and carrying a ring traveller adapted to revolve about the bobbin in the orbit prescribed by the ring. A snubbing pin bet-ween the draw roll and feed rolls is usually used to better control the point of draw. The draw roll runs faster than the feed rolls in order to stretch the yarn as desired, and the ring twister twists the yarn and winds it on the bobbin simultaneously and continuously. Ordinarily, the yarn is drawtwisted throughout package formation at the fastest possible speed for economic reasons. The drawtwisting speed is uniform, and no steps are usually taken to periodically vary the speed during the building of a given package. The peripheral speed of the yarn package, the speed of the yarn being forwarded to ring twister assembly, the weight of the traveller, and air currents surrounding the package are some of the factors that determine the Wind-up tension. These factors cause minor tension variations throughout the package building.

While continuous filament yarns have the advantage of greater evenness and superior strength, they have several undesirable properties including low heat insulation values, lack of bulkiness desired for some end uses, and low covering power. Many ways have been used to impart a more voluminous character to continuous filament yarn. Yarns having such character are referred to as having been textured. One texturing method involves heat setting a high twist imparted to a yarn and then reducing the twist. The twisting and untwisting operation is most conveniently accomplished by a false-twisting technique. False-twisting devices for texturing nylon filament yarns are well known. Since false-twist texturing is relatively a slow operation, continuing efforts are made to operate the devices at the highest possible speed.

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Coinciding with the use in the texturing yarn trade of high speed false-twist equipment, an intermittent, undesirable pebbled or terry cloth effect appears in finished fabric made from normal drawtwisted, false-twist textured, nylon filament yarn. Upon closer examination, it has been found that the yarn composing the fabric defect had a strength loss due to texturing averaging up to 50% of the original yarn strength, but that the yarn composing the remainder of the fabric had a strength loss averaging only 20-30% of its original tensile strength. Further study has revealed that the yarn showing the high loss of strength was that portion of yarn first wound on a bobbin during the drawtwisting operation. The portion of the yarn on the bobbin giving rise to fabric defect, in the main, constitutes about 1 to 8 ounces of the yarn on the drawtwist bobbin. In addition to the loss of strength, the minor portion of the yarn located nearest the bobbin dyes differently from the remainder. To avoid the pebbled effect the minor portion of the yarn heretofore would have to be discarded in order to produce a high quality fabric. It has been found that the strength loss throughout the textured yarn package could be minimized by changing the texturing conditions, i.e., by increasing the overfeed to the false-twist spindle from about 26%. These changes in texturing conditions, however, resulted in unsatisfactory or non-commercial textured yarn, as well as in poorer yields from the false-twist texturing apparatus.

It is a primary object of the present invention to provide a method of drawing and packaging nylon filament yarn whereby strength loss in the initially packaged yarn normally occurring from texturing thereof is reduced.

Another object ofthe invention is to provide a method of draw-twisting and packaging nylon filament yarn whereby strength loss and other undesirable effects in the initially packaged yarn normally occurring from falsetwisting yarn are reduced in their severity.

Other objects may become apparent from the following detailed description.

In accordance with the present invention a method is provided for drawing and packaging nylon filament yarn such that the packaged yarn when false-twist-textured exhibits a uniform strength and dyeability throughout its length. This is accomplished by forwarding undrawn nylon filament yarn from a source to a draw zone. The yarn is withmawn from the zone at an increased speed to draw the yarn at substantially the natural draw ratio. Next, the yarn is twist-wound on a rotating bobbin to form a package of yarn. During the winding, the yarn is traversed along the bobbin at a tension sufficient for package formation. After a minor portion of the yarn constituting about 1 to 8 ounces of the resulting package has been drawn and packaged, the speed of the yarn being drawn and the speed of yarn wind-up are increased to provide a substantial increase in the tension of the yarn being wound. While a single step involving the required increased yarn speeds and tension will ordinarily suifice, a plurality of steps may be taken periodically such that during each succeeding step increased speeds and tensions are employed.

. The yarn source can be a yarn package previously doifed from a conventional melt-spinning machine or can be one preceding directly from such a machine without any intermediate packaging. Hence, the yarn will have little or no twist. The yarn is capable of being molecularly oriented and is made from fiber-forming nylon polymer. Examples of nylon polymer include: polymeric (hexamethylene adipamide), referred to as nylon-66; polymeric (hexamethylene sebacamide), referred to as nylon-610; and polymeric (6-amino caproic acid), referred to as nylon-6. The process is also applicable to yarn made from nylon-4, nylon-7, nylon-11, mixtures of nylon polymers and copolymers thereof, e.g., nylon 6/66, 6/610/66, 66/610, etc. While the present process is suitable for treatment of yarn whose filaments have a normal round cross section, yarns having a non-circular or lobular cross section, or having an axial passage can also be used.

The undrawn nylon yarn is forwarded from the source to a draw zone where the yarn is stretched continuously to greatly increase the strength and the degree of molecular orientation. This drawing is accomplished by a yarn forwarding means and a yarn drawing means, the latter pulling the yarn at an increased speed to provide a draw ratio of about 1.9 to 5.0. The draw ratio is the number obtained by dividing the speed of the yarn fed to the zone by the speed of the yarn leaving the zone. On e form of apparatus for stretching the yarn is a pair of nip-forming feed rolls and a draw roll on a conventional drawtwister for synthetic filament yarn. A common term used to describe the draw ratio for a given set of conditions is the natural draw ratio. This amount of draw results in an extension of the filaments sufficient to change them from their undrawn state to a uniformly drawn and highly oriented state without straining them to introduce surface cracks or filament breaks. When one employs a draw ratio lower than the natural draw ratio, some of the sections of the filaments will draw at the natural draw ratio while other sections will remain undrawn. The ratio depends on the temperature, moisture or other plasticizer content of the yarn, the rate of drawing, snubbing, etc.

After being stretched in the draw zone, the yarn is wound on a rotating bobbin to form a package of yarn. This normally is accomplished by the use of a ring twister assembly so that the yarn is twisted and wound in one step at a suitable tension provided by the traveller of the twister assembly. It has been found that the uniformity of strength retained in the yarn after being textured and of dyeability is obtained primarily by controlling the wind-up tension during the drawtwist processing of the nylon yarn. A relatively slow yarn speed and bobbin speed are used for the initial 1 to 8 ounces of yarn wound on the bobbin. The initial wind-up tension is low and in the order of 0.01 to 0.07 gram per denier. Higher yarn speeds are used for the remainder of the package building operation. At the higher speeds a natural draw ratio will still be used but the traveller races around the ring at an increased velocity, causing the yarn to be wound up at an increased tension in the order of 0.1 to 0.4 gram per denier. A twist of about 0.1 to 0.5 turn per inch is used to maintain commercial productivity.

In order to obtain a nylon yarn of uniform texturability throughout the supply package for a 70 denier yarn composed of 34 filaments weighing about four pounds, about the first 6 ounces of drawn yarn should be wound on the bobbin with a minimum tension, i.e., just sufficient tension for wind-up. A tension on a 70 denier yarn of below grams is quite adequate. The low tension allows for a minor but controlled retraction of the drawn yarn. Full retraction in this region of the package, however, is prevented because of the restriction of the bobbin and the compression of the outer yarn. After the minor portion of the yarn constituting about 1 to 8 ounces of the ultimate package has been drawtwisted and packaged, the remainder of the yarn is taken up at a tension about 2 to 3 times greater than the tension during initial Wind-up. The low beginning tension is best attained by operating the drawtwister with a low yarn speed and low bobbin speed initially. The higher tensions in the terminal stage are best achieved by increasing the yarn speed and the spindle speed after the requisite amount of yarn is taken up, the traveller not being changed. This results in a package of yarn that has substantially uniform retraction throughout.

The process of the invention results in a yarn having uniformed texturability as indicated by the percentage of strength retained after having been textured. In the attached drawing a graph is given plotting the percent breaking strength retained after a 70 denier nylon filament yarn has been false-twist textured at a high speed as a function of the location of the yarn removed from the resulting package of textured yarn. The broken line illustrates the strength characteristics of yarns processed by the present invention, and the solid line illustrates the strength characteristics of yarns processed at one set of drawtwist conditions as normally employed in the trade. It is to be noted that the textured yarn treated by the process of the present invention retains throughout the package at least 70% of its original strength and the loss is relatively uniform throughout. On the other hand, the first few ounces of textured yarn not drawn by the process of the present invention has a loss up to 50% of its original strength and such loss varies considerably throughout the package of textured yarn.

The controlled yarn speeds and tension in the two step drawtwisting can be obtained by any suitable variable speed drives used in connection with drawtwisters. A programmed two-speed motor arrangement is preferred because it is the most economical way for producing a commercially acceptable product. Programmed Eddy current drives, mechanical variable speed drives, and alternator-supplied current provide greater flexibility of speeds and also a more uniform product.

The following examples will serve to illustrate the invention but are not intended to be limitative thereof. The yarn employed in each case was melt-spun from nylon-66 to form 34 filaments having an ultimate denier of 70. On deniers above 70 the take-up tensions during the slow speed step and the faster speed step of the drawtwisting process will ordinarily range higher. On yarns below 70 denier the tension during the low and high speed steps will ordinarily range lower.

Example I A 34 filament nylon-66 yarn having a relative viscosity of about 40 with a spun denier of 280 was pulled from a spin bobbin package and passed over a pre-tension guide by means of a conventional drawtwister feed and top-cot roll assembly. The yarn then was fed around a drawpin with two wraps being taken therearound. Five wraps of the yarn were made around a matte-finish draw and separator roll arrangement. Thereafter the yarn was packaged, employing a ring twisting assembly. The take-up package was 13" in overall length, and the bobbin diameter was 1%". The ring traveller was a size 27 Carter AR-586RW.

Stage 1.During the drawing and packaging of the first 6 ounces of yarn which took about 53 minutes, the yarn was fed by the roll assembly at yards per minute and forwarded by the draw roll at 480 yards per minute to provide a draw ratio of 2.47. The spindle speed driving the bobbin was 5200 revolutions per minute. The average take-up tension at this low initial speed was 2.5 grams. The twist in the yarn averaged 0.31 t.p.i.

Stage 2.--The feed roll, draw roll and spindle speeds were increased. The yarn was forwarded at 390 yards per minute by the feed roll and at 964 yards per minute by the draw roll. The spindle speed was 10,400 I'.P.1Il. At these high speeds the yarn was packaged for an additional 240 minutes to form a 3.5 pound package, and the takeup tension averaged 8.8 grams. The twist in the portion of the yarn wound during stage 2 was 0.31 t.p.i.

The thus-drawn yarn was textured on a 553 Superloft machine manufactured by the Leesona Corp. of Providence, R.I. This machine is adapted for false-twist texturing of nylon filaments. During the texturing the falsetwist spindle was operated at 240,000 r.p.m. The overfeed of the yarn at the bottom was 4% and at the top was The twist insert in the yarn was 76 t.p.i., and the heater was operated at 458 F. The texturing conditions were used for all yarn processed in accordance with the examples herein.

The textured yarn obtained by this example displayed 1) an excellent strength uniformity throughout the package as shown by the broken line in the drawing; (2) excellent intrabobbin and interbobbin dyeing uniformity with a critical premetalized acid dye (Irgalan Brown 26L); and (3) no pebbled etfect in fabric.

EXAMPLE II Spun yarn having the same history as the spun yarn in Example I was processed on the same drawtwister with the following execptions: (1) the entire package was packaged at one spindle speed of 12,800 r.p.m., (2) the entire drawn yarn speed was 870 yards per minute; and 3) a 26 Carter AR-586 RW traveller was used. At these conditions the yarn was packaged at 14-22 grams throughout the 3.5 pound package and was twisted 0.41 r.p.i. The yarn was then false-twist textured as described in Example I. The textured yarn showed ('1) poor strength retained for the run-out portion of the supply package as shown by the solid line in the drawing; (2) the textured yarn from the run-out section exhibited an undesirable pebbled effect resulting in luster variation in knit goods; and (3) poor intrabobbin and interbobbin dyeing uniformity with acid dye Irgalan Brown 2GL.

EXAMPLE III Yarn having the same history as the above examples was used and processed on a drawtwister producing the same type of package (warp wind). In this case the yarn was packaged with a low tension of 2-4 grams throughout the package. This was done by using (1) a spindle speed of 56 55 rpm, (2) a drawn yarn speed of 582 y.p.m. giving a twist of 0.2.7 t.p.i., and (3) a 27 Carter AR-586 RW traveller. The yarn was then textured on the same texturing machine as described in Example I. This textured yarn showed a strength retained of 80% for the run-out section of the package which is acceptable. The strength retained for the middle and outside sections was 97%; however, the yarn was not lastingly twist-textured. This made the yarn unacceptable.

From the above it is seen that Examples I and II show that low wind-up tensions are needed for the run-out yarn and high tensions for the remaining supply package are needed to obtain a yarn package acceptable to the falsetwist texturing trade. Example III shows that if low tensions are used throughout the package, the textured yarn of the run-out section is acceptable but not the textured yarn from the rest of the package.

Numerous advantages are associated with the present process. One is able to produce a false-twist textured nylon yarn having improved strength uniformity throughout its length. The textured yarn also has improved dye uniformity throughout its length. The textured yarn also has improved dye uniformity and fabric made therefrom has an improved appearance. Other advantages may be noted.

Any departure from the description herein that conforms to the spirit of the invention is intended to be included within the scope of the following claims.

What is claimed is:

1. A method of drawing and packaging nylon filament yarn comprising:

(a) forwarding undrawn nylon filament yarn from a source to a draw zone;

(b) withdrawing the yarn from the zone at an increased speed to draw the yarn molecularly;

(c) winding the yarn on a rotating bobbin to form a package of yarn;

(d) traversing the yarn along the bobbin at a tension sufficient for package formation; and

(c) after a minor portion of the yarn constituting about 1 to 8 ounces of the resulting package has been drawn and packaged, increasing the speed of the yarn being drawn and the speed of the yarn wind-up to provide a substantial increase in the tension of the yarn being wound;

whereby strength loss in the initially packaged yarn normally occurring from texturing thereof is reduced.

2. A method of drawtwisting and packaging nylon filament yarn comprising:

(a) forwarding undrawn nylon filament yarn from a source to a drawn zone;

(b) withdrawing the yarn from the zone at an increased speed to draw the yarn at substantially the natural draw ratio;

(c) twisting the yarn and simultaneously and continuously winding the yarn on a bobbin to form a package;

(d) traversing the yarn along the bobbin at a tension just sufficient for package formation; and

(e) after a minor portion of the yarn constituting about 1 to 8 ounces of the resulting package has been drawn and packaged, increasing the speed of the yarn being drawn and the speed of yarn wind-up to provide a substantial increase in the tension of the yarn being wound without substantially changing the twist being imparted in the yarn;

whereby strength loss in the initially packaged yarn normally occurring from texturing thereof is reduced.

3. A method of drawtwisting and packaging nylon filament yarn comprising:

(a) forwarding undrawn nylon filament yarn of substantially zero twist from a source to a draw zone;

(b) withdrawing the yarn from the zone at an increased speed to draw the yarn at substantially the natural draw ratio;

(c) twisting the yarn and simultaneously and continuously winding the yarn on a bobbin to form a package;

(d) traversing the yarn along the bobbin by use of a reciprocating ring holding an orbiting traveller which provides on the yarn being wound a tension of about 0.01 to 0.07 gram per denier; and

(e) after a minor portion of the yarn constituting about 1 to 8 ounces of the resulting package has been drawn and packaged, increasing the speed of the yarn being drawn and the speed of yarn wind-up to provide an increased tension on the yarn of about 0.1 to 0.4 gram per denier without substantially changing the twist being imparted in the yarn;

whereby strength loss in the initially packaged yarn normally occurring from texturing thereof is reduced.

4. A method of drawtwisting and packaging nylon filament yarn comprising:

(a) forwarding undrawn nylon filament yarn of substantially zero twist from a source to a draw zone;

(b) withdrawing the yarn from the zone at an increased speed to draw the yarn at substantially the natural draw ratio;

(c) twist winding a minor portion of the yarn on a bobbin to form a package rotating at a speed to impart a twist of about 0.1 to 0.5 turn per inch in the yarn;

(d) traversing the yarn along the bobbin by use of a reciprocating ring holding an orbiting traveller which provides on the yarn being wound a tension of about 0.01 to 0.07 gram per denier;

(e) after the minor portion of the yarn constituting about 1 to 8 ounces of the resulting package has been draw-twisted and packaged, increasing the speed of the yarn being drawn and the speed of yarn windup to provide an increased tension on the yarn References Cited $35 55? 25 a; in 'th e ii visi fiti f f; i r t in iii UNITED STATES PATENTS yam; 2 g g g P 2,944,382 7/1960 Batty et a1. 57-62 (f) maintaining the increased speeds and tension 5 29703424 2/1961 Bauer 57*62X 3 258 904 7/ 1966 W1nterbottom et a1. 5734 h h th k t mug e remamder of pac age formaton 3,277,641 10/1966 ODonahue et a1 57 157 whereby strength loss in the initially packaged yarn normally occurring from texturing thereof is reduced.

5. The method of claim 4 wherein the nylon is ny- FRANK COHEN Prlmary Examiner Ion-66. 10 J. PETRAKES, Assistant Examiner. 

1. A METHOD OF DRAWING AND PACKAGING NYLON FILAMENT YARN COMPRISING: (A) FORWARDING UNDRAWN NYLON FILAMENT YARN FROM A SOURCE TO A DRAW ZONE; (B) WITHDRAWING THE YARN FROM THE ZONE AT AN INCREASED SPEED TO DRAW THE YARN MOLECULARLY; (C) WINDING THE YARN ON A ROTATING BOBBIN TO FORM A PACKAGE OF YARN; (D) TRAVERSING THE YARN ALONG THE BOBBIN AT A TENSION SUFFICIENT FOR PACKAGE FORMATION; AND (E) AFTER A MINOR PORTION OF THE YARN CONSTITUTING ABOUT 1 TO 8 OUNCES OF THE RESULTING PACKAGE HAS BEEN DRAWN AND PACKAGED, INCREASING THE SPEED OF THE YARN BEING DRAWN AND THE SPEED OF THE YARN WIND-UP TO PROVIDE A SUBSTANTIAL INCREASE IN THE TENSION OF THE YARN BEING WOUND; 